The Rozière balloon (or simply Rozière) is a type of hybrid balloon that has separate chambers for a non-heated lifting gas (in our case, helium) as well as a heated lifting gas (as used in a hot air balloon or Montgolfière). This type of aircraft takes its name from its creator, Jean-François Pilâtre de Rozier.
The advantage of a Rozière is that it allows some control of buoyancy with much less use of fuel than a typical hot air balloon. This reduction in fuel consumption has allowed Rozière balloons and their crew to achieve very long flight times, up to several days or even weeks.
The first Rozière was built for an attempt at crossing the English Channel on 15 June 1785.
Today, Rozière designs use non-flammable helium rather than hydrogen. Their primary application is for extremely long duration flights. They have been used for all the round-the-world balloon flights.
Deborah & Mike's balloon has been built by Cameron Balloons in Bristol. Its designation is R77GB (Rozière, 77,000cuft, Gas Balloon). The registration is G-ZOZO (affectionately known as Golf-2020). The serial number is 12247.
The lift is provided by a gas cell at the top of the balloon filled with helium. A fabric cone hangs from the middle of the gas cell with its narrow end attached to the frame of a small double burner, mounted on poles above the basket. In order to maintain a level flight, the volume of the gas cell needs to be constant. At night, to stop the gas cell cooling and so reducing in size, the burner is used to warm the air in the cone which in turn warms the gas cell and maintains its volume.
The balloon is composed of a gas cell and a warm air cone. The estimated weight of the fabric and lines is 275 kg. It is 27 metres high and 17 metres in diameter. The gas cell is 77,000 cubic feet or 2,180 cubic metres. The cone is 15,000 cubic feet (approx.) or 425 cubic metres.
The gas cell is constructed of a strong impervious fabric which is coated with carbon-based liquid on the inside to transmit any static electricity. The small burner is powered by liquid propane. The pilot lights for the burner use propane vapour which is drawn from the top of the propane tanks. There are 8 titanium tanks that will be suspended from the burner frame and mounted around the outside of the basket.
A specially designed stainless steel chimney valve is mounted at the top of the gas cell to allow the venting of helium in order to change height.
Two fabric chimney valves are sewn into the fabric to enable the gas to be vented after the final landing. Once these have been opened by the pilot they cannot be closed. These two valves enable quick deflation should the balloon land in breezy conditions.
The basket is approximately 1.75 x 1.2 metres internally and about 1.25 metres high and made from traditional willow-lined inside and out with a space blanket. There will be a polythene cover suspended from the burner frame to keep warmth in at night and act as a rain cover. There will also be a sunshield as UV radiation is stronger at altitude.
A 50 metre trail or drag rope which is attached to the burner frame is thrown from the basket shortly before landing. Once dragging on the ground this turns the balloon to face the correct way for landing as well as slowing it down. This is a rough fibre made from coconut-based products.
Sandbags holding 15 kilos of fine kiln dried sand mixed with rock salt to prevent it freezing solid at altitude are carried as ballast. These are emptied to lighten the balloon when Debbie & Mike need to climb higher and to reduce the rate of descent when landing should they need to conserve propane.
A summary of what the basket will contain:-
A lightweight seat.
Approximately 70 litres of drinking water.
Enough food for 10 days. This will include porridge, dried food packs for main meals, coffee, earl grey tea, fruit cake and snacks.
A compact fast water heater will be used to provide hot water for drinks and to heat expedition dried food packs.
A strap mounted around the top edge of the basket will be used to hang lightweight solar panels, equipment and to air clothes during the day.
Two lightweight carbon fibre oxygen cylinders for use when flying above 10,000 feet (which may be necessary to go over the top of bad weather or to make a substantial change of direction).
Lightweight camping toilet with heavy-duty greaseproof biodegradable paper bags.
Red lights for night vision.
Mode S Transponder which shows air traffic controls and pilots height and position.
Aviation radios to talk to air traffic controllers and other aircraft.
Two handheld Icom marine band radios to talk to shipping and for emergency use.
An electronic map that shows the balloon’s position in relation to airways and controlled airspace.
Two altimeters with GPS.
A satellite tracker which will display our position, height, speed and direction on a website so the public can follow our adventure.
Spare rechargeable lithium-ion phosphate batteries to power the equipment. These are recharged from the solar panels.
Thermal underwear with Merino wool for top insulation, worn next to the skin (even effective when damp).
Arctic clothing (Air temperature drops by 2 degrees C for every 1,000 feet gain in altitude).
Mountaineer sleeping bags.
Lightweight sheepskin footwear.
Sea survival kit:-
Life jackets and an inflatable life raft.
Personal locator beacons.
Grab bag containing food and water.
Marine band radios.